This application is based on and claims priority under 35 U.S.C. xc2xa7119 with respect to Japanese Applications No. 2000-261789 filed on Aug. 30, 2000 and No. 2001-085485 filed on Mar. 23, 2001, the entire content of which is incorporated herein by reference.
1. Field of the Invention
This invention generally relates to entrapment detection device. More particularly, the present invention pertains to entrapment detection device for an opening/closing member for opening and closing a fixed member and control thereof.
2. Background of the Invention
Recent vehicles including an opening/closing member such as a sunroof and wind regulators are generally provided with a safety mechanism. When the opening/closing member is operated by a motor, the safety mechanism detects entrapped objects or obstacles, stops the opening/closing member, and moves the opening/closing member in a reverse direction when the entrapment of the an object or obstacle is detected.
In known methods, the entrapment of obstacles is detected by the fluctuation of motor torque. A rotational condition of a motor for actuating the opening/closing member is detected by a rotation detecting sensor including a hall element. The entrapment is detected based on a pulse signal from the rotation detecting sensor.
Japanese Patent Laid-Open Publication No. H06-280446 discloses an opening/closing control device for judging the occurrence of the entrapment condition when a drive speed and a drive acceleration of the motor for opening/closing member operation is less than a predetermined threshold value determined based on a drive speed and the drive acceleration of the opening/closing member. The opening/closing control device detects the rotation of the motor for actuating a power window by a motor position detecting sensor and calculates a motor rotation speed and a motor rotation acceleration. The opening/closing control device performs feedback/reverse control by comparing the motor rotation speed with a speed threshold value when a motor rotation speed change is regular. Alternatively, the opening/closing control device performs reverse control by comparing the motor rotation acceleration with an acceleration threshold value when the motor rotation speed change is not regular.
Japanese Patent Laid-Open Publication No. H08-4416 discloses an entrapment prevention device which detects the entrapment of obstacles when a window pane is at a position range at which the pane possibly causes an entrapment, when the relative speed is greater than a predetermined value, when a number of successive speed changes occur while closing the pane, and a total of each amount of speed change is greater than a predetermined value. In the entrapment prevention device, a motor rotational condition for actuating the pane is obtained in the following manner. An edge interval time Tn is detected by sensing a time interval of the pulse signal, angular speed component data Fn is obtained from the inverse of the edge interval time (Fn=1/Tn), electric voltage correction data and a relative speed Vn are obtained, and the total relative speed DVn is calculated. When the total relative speed DVn is greater than a predetermined value, an entrapment condition is determined to exist.
Japanese Patent Laid-Open Publication No. H08-128259 discloses a window opening/closing control device for judging whether obstacles are entrapped by predetermining a threshold value for judging whether obstacles are entrapped based on a cycle (period) corresponding to an output interval of the pulse signal from the hall element during the closing operation of the window. The window opening/closing control device reads the cycle of the pulse signal of a sensor for detecting the rotation of the motor for driving window within the range within which entrapment possibly occurs. The window opening/closing control device further identifies the relationship between a cycle range xcex94Ti, and a threshold value (mi) from a map, calculates a pulse signal cycle differentiation xe2x88x9d, and detects the entrapment of the obstacles by the pulse signal cycle differentiation xe2x88x9d.
However, the known devices disclosed in the Japanese Patent Laid-Open Publication H06-280446 and the Japanese Patent Laid-Open Publication H08-4416 are required to obtain the rotational speed of the motor. In order to obtain the rotational speed of the motor, the aforementioned known devices are required to perform a division operation in the process of the calculation of the reciprocal of the pulse cycle. Generally, the division operation requires a longer calculation time compared to addition, subtraction, and multiplication operations. This increases the size of the program. Because entrapment is judged after considering the rotation cycle and performing the calculation in the controller, it takes time for judging the entrapment after detecting the data of entrapment.
If it takes time to determine an entrapment condition when the rotational speed of the motor suddenly decreases and when the entrapment occurs such as the case that a hard object is entrapped, the entrapment load (load on the entrapping member) is increased. Further, when the pulse output is not inputted into the controller from a sensor, such as when the sensor for detecting the rotation of the motor is damaged, judgment of the entrapment cannot be performed.
In the known method in which a map is used at the judgment of the entrapment is disclosed in the Japanese Patent Laid-Open Publication No. H08-128259, the information necessary for the judgment of the entrapment needs to be memorized (stored in memory) previously, which increases a memory size.
Therefore, a need exists for an entrapment detection device of an opening/closing member which quickly determines entrapment without using a division operation necessary for calculating the motor rotational speed at the judgment of the entrapment.
According to one aspect of the invention, an entrapment detection device of an opening/closing member includes a motor for actuating the opening/closing member, a detecting means for outputting a pulse synchronized to movement of the motor, and a control means for performing an entrapment detection during an operation of the opening/closing member based on a change of the pulse output from the detecting means. The control means memorizes (stores in memory) a change of the pulse output of a predetermined number of pulses, predetermines a standard cycle, Tb, from the memorized pulse output, calculates a cycle coefficient, Cb, for a cycle in which no entrapment is detected based on the standard cycle Tb, and performs an entrapment confirmation by comparing a multiplied value based on the cycle coefficient Cb, the latest cycle interval time Tn and the standard cycle Tb.
According to another aspect of the invention, an entrapment detection device of an opening/closing member includes a motor for actuating the opening/closing member, a detecting means for outputting a pulse synchronized to movement of the motor, and a control means for performing an entrapment detection during an operation of the opening/closing member based on a change of the pulse output from the detecting means. The control means memorizes output changes of the pulse output, obtains the latest cycle interval time Tn, predetermines a standard cycle Tb from an output pulse several pulses before, calculates a cycle coefficient Cb based on the standard cycle Th, and performs an entrapment confirmation when a multiplied value based on the cycle coefficient Cb and the cycle interval time Tn is greater than the standard cycle Tb.